1.4 Sea-Floor Spreading

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Vocabulary

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Mid-Ocean Ridge- the longest chain of mountains in the world
Sonar- a device that bounces sound waves off underwater object
Sea-Floor Spreading- a process that continually adds new material to the ocean floor
Deep-Ocean Trenches- the ocean floor plunges into deep underwater canyons
Subduction- the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle

Outline

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Mapping the Mid-Ocean Ridge
-the longest chain of mountains in the world
-in the mid 1900, scientists mapped the mid-ocean ridge
-curces like the seam of a baseball along the sea floor
-Iceland is part of the mid-ocean ridge

Evidence for Sea-Floor Spreading
-the mid-ocean ridge forms a crack in the ocean crust
-molten material com out and the older rocks move aside
-three evidences, evidence from molten material, evidence from magnetic stripes, evidence from drilling samples

Subduction at Deep-Ocean Trenches
-pushing the ocean floor down
-convection

Subduction and Earth's Oceans
-subduction could change size of oceans
-subduction in the Pacific Ocean
-subduction in the Atlantic Ocean